CA2026548C - Condenser-reactor switching units for extended claus process - Google Patents
Condenser-reactor switching units for extended claus processInfo
- Publication number
- CA2026548C CA2026548C CA002026548A CA2026548A CA2026548C CA 2026548 C CA2026548 C CA 2026548C CA 002026548 A CA002026548 A CA 002026548A CA 2026548 A CA2026548 A CA 2026548A CA 2026548 C CA2026548 C CA 2026548C
- Authority
- CA
- Canada
- Prior art keywords
- condenser
- claus
- sulfur
- reactor
- pressure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000000034 method Methods 0.000 title claims abstract description 46
- 230000008569 process Effects 0.000 title claims abstract description 43
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 87
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 86
- 239000011593 sulfur Substances 0.000 claims abstract description 86
- 238000001179 sorption measurement Methods 0.000 claims abstract description 16
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 5
- 239000007789 gas Substances 0.000 claims description 60
- 230000003197 catalytic effect Effects 0.000 claims description 30
- 230000007704 transition Effects 0.000 claims description 27
- 238000011084 recovery Methods 0.000 claims description 19
- 238000001816 cooling Methods 0.000 claims description 13
- 238000004891 communication Methods 0.000 claims description 9
- 239000002918 waste heat Substances 0.000 claims description 2
- 230000015572 biosynthetic process Effects 0.000 claims 1
- 241000196324 Embryophyta Species 0.000 description 59
- 238000004519 manufacturing process Methods 0.000 description 11
- 238000006243 chemical reaction Methods 0.000 description 9
- 208000036366 Sensation of pressure Diseases 0.000 description 7
- 230000008929 regeneration Effects 0.000 description 7
- 238000011069 regeneration method Methods 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 239000003054 catalyst Substances 0.000 description 6
- 206010037660 Pyrexia Diseases 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 239000012808 vapor phase Substances 0.000 description 2
- DTAFLBZLAZYRDX-UHFFFAOYSA-N OOOOOO Chemical compound OOOOOO DTAFLBZLAZYRDX-UHFFFAOYSA-N 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000000112 cooling gas Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000000994 depressogenic effect Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 239000002737 fuel gas Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000036316 preload Effects 0.000 description 1
- 230000002277 temperature effect Effects 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/02—Preparation of sulfur; Purification
- C01B17/04—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides
- C01B17/0404—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by processes comprising a dry catalytic conversion of hydrogen sulfide-containing gases, e.g. the Claus process
- C01B17/0426—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by processes comprising a dry catalytic conversion of hydrogen sulfide-containing gases, e.g. the Claus process characterised by the catalytic conversion
- C01B17/0439—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by processes comprising a dry catalytic conversion of hydrogen sulfide-containing gases, e.g. the Claus process characterised by the catalytic conversion at least one catalyst bed operating below the dew-point of sulfur
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/02—Preparation of sulfur; Purification
- C01B17/04—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides
- C01B17/0404—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by processes comprising a dry catalytic conversion of hydrogen sulfide-containing gases, e.g. the Claus process
- C01B17/0447—Separation of the obtained sulfur
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
- Y02P20/129—Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Treating Waste Gases (AREA)
- Separation Of Gases By Adsorption (AREA)
Abstract
A reactor unit for use in extended Claus process plants comprising three or more reactor units, each alternating between operation under high temperature Claus and cold bed adsorption conditions, comprises a sulfur condenser upstream of an associated downstream reactor which are rotated as a unit through operations in the plant. This reduces the number of condensers required. In a further aspect, a potential surge in the plant low pressure steam system is eliminated in comparison with previous similar extended Claus plants.
Description
-' ~ 2~2~48 PATENT
Pendergraft, P. T.
CONDENSER-REACTOR SWITCHING UNITS FOR
EXTENDED CLAUS PROCESS
FIELD OF THE INVENTION
The invention relates to extended Claus sulfur recovery plants and processes of the type having at least three reactors each periodically operated alternately under high temperature Claus and under CBA conditions and 15 particularly to reactor switching units for such plants.
In another particular aspect, the invention relates to such plants and processes which require fewer sulfur con-densers than a prior art design. In another particular aspect, the invention relates to such plants and processes 20 which prevent a high pressure to low pressure transition in a condenser from affecting emissions from the sulfur plant.
SETTING OF THE INVENTION
An extended Claus sulfur recovery plant com-prises one or more catalytic reactors operated under high temperature Claus conditions in series with one or more catalytic reactors operated under cold bed adsorption (CBA) conditions. Under high temperature Claus condi-2 0 2 6 ~i ~ 8 tions, sulfur formed in presence of Claus catalyst is con-tinuously removed from the reactor in vapor phase and condensed in a sulfur condenser. Under CBA conditions, most sulfur formed is deposited and accumulated on the 5 Claus catalyst. The sulfur is periodically removed during regeneration by effective high temperature gas flowing through the reactor and vaporizing sulfur which is with-drawn in vapor phase from the reactor and condensed in a sulfur condenser. High temperature Claus operation and 10 regeneration can occur concurrently.
Besides condensing sulfur, shell-and-tube indi-rect heat exchangers used as sulfur condensers produce useful steam. In such shell-and-tube exchangers, boiler feed water in the shell side is converted to steam while 15 in the tube side process gas containing sulfur vapor is cooled and sulfur is condensed and removed. For purposes of discussion, steam production on the shell side and gas cooling and sulfur condensation on the tube side is assumed. However, steam production on the tube side and 20 process gas cooling and sulfur condensation on the shell side can also be used.
Where the process gas after cooling is above about 300~F, high pressure (for example, 60 psig) steam can be produced. When the process gas after cooling is 25 below about 300~F down to about 260~F, only low pressure steam (for example, 15 psig) can be produced. High pres-sure steam has many uses in plants and represents signif-icant economic advantage relative to low pressure steam which has fewer applications. It is desirable to maximize 2~2~
high pressure steam production and to produce low pressure steam only when high pressure steam cannot be produced consistent with efficient and cost effective design and operation of the sulfur plant.
In extended Claus processes, sulfur condensers cooling gas for introduction into CBA reactors typically operated at temperatures less than 300~F generally produce only low pressure steam whereas sulfur condensers feeding high temperature Claus reactors or ~Iwarm~l CBA reactors can 10 be used to produce high pressure steam. When a reactor is alternated between llwarmll and llcoolll CBA and high temper-ature Claus operations concurrent with regeneration, a condenser feeding that reactor sometimes produces low pressure steam and sometimes produces high pressure steam.
In the type of extended Claus sulfur recovery plant in which three or more reactors are each period-ically alternated between CBA and high temperature Claus conditions, conventional plant design associates a sulfur condenser with a reactor and rotates the reactor/condenser 20 pair as a unit. Such a plant is shown in FIGURE 1 - PRIOR
ART. TABLE A identifies reference numerals in FIGURE 1 for easy identification.
' ~26~
t - TABLE A
Symbol Refers To FURN/WHB Claus furnace (FURN) with waste heat boiler (WHB) CF Furnace sulfur condenser Va WHB bypass reheat valve Rv Claus reactor (dedicated to high temperature Claus operation) Cv Claus reactor condenser Vb Claus reactor condenser bypass reheat valve A Claus/CBA Reactor Unit A
B Claus/CBA Reactor Unit B
15 C Claus/CBA Reactor Unit C
1,1' Process gas supply to reactor from unit Cv or another reactor or reactor unit 2 Alternate process ~as supply to reactor unit from another reactor unit 20 3 Reactor effluent line 4 Condenser effluent line Effluent line to another reactor unit 6 Effluent line to tail gas (TG) disposal 7 High pressure steam (HPS) line 25 8,8' Low pressure steam (LPS) line 9 Liquid sulfur (S) outlet ~oiler feedwater (BFW) line 13 Timer/controller for valves ~02~548 TABLE 1 shows steam production and operation sequences for operation of the FIGURE 1 plant. In the FIGURE 1 plant, reactor Rv is operated only as a first Claus reactor ("Claus l") while reactors Ra, Rb, Rc alter-5 nate hetween CBA operation and Claus operation. (Note: A
~eactor operated under high temperature Claus conditions may be referred to as a Claus reactor; likewise, a reactor operated under CBA conditions may be referred to as a CBA
reactor - both Claus and CBA reactors catalyze the Claus 10 reaction.) A reactor previously operated under CBA condi-tions which is being regenerated in the second position also operates as a second Claus reactor ("Claus 2"). CBA
operation in the FIIJURE l plant occurs when a reactor is in the third and fourth positions. The third position 15 reactor, after precooling to CBA operation conditions, is generally operated as a "warm" CBA (feed temperature above 280-300~F or more) and the fourth position reactor is gen-erally operated as à "cool" CBA reactor (feed temperature about 250-260~F) for maximum recovery. Regeneration in 20 the second position concurrently with Claus 2 operation includes heatup, plateau, and heat soak as is known to those skilled in the art (see U.S. Patents 4,482,532, B. E. Cabanaw, issued November 13, 1984 and 4,822,591, R. L. Reed, J. W. Palm, issued April 18, 1989) Precooling of a newly regenerated reactor is accomplished prior to returning a reactor to CBA operation. These steps individually are well known to those skilled in the art, and from FIGURE 1 .. ~ L
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and TABLE 1 those skilled in the art will fully understand the se~uence of operation.
One problem with the FIGURE 1 plant is that in each of the modes of operation, there is always a conden-5 ser following the final CBA reactor. The gas leaving thisreactor is normally cool (less than 280~F) with a sulfur dewpoint depression of 50 to 80~F. Therefore, no sulfur will condense from this gas above the sulfur freezing point of about 235~F. Running this gas through a conden-10 ser just cools it with no benefit (except, perhaps, thesmall amount of steam which would be produced) and with the detriment that more fuel gas will be re~uired in the incinerator to dispose of the cooled tail gas.
Another problem with the FIGURE 1 plant arises 15 from the practice of switching a condenser from a high pressure environment to a low pressure environment during certain portions of the operating cycle. This practice periodically overloads the low pressure steam delivery system resulting in an increase in emissions from the 20 plant. This problem is discussed below in more detail.
A preferred precooling method for the FIGURE l plant is a "backstep," such as precooling in mode C fol-lowing regeneration in Mode A and prior to switching to Mode B, as this method does not preload with sulfur a 25 freshly regenerated reactor before it is placed under CBA
conditions.
The three condensers Ca, Cb, Cc are tied to both low pressure steam (LPS) and high pressure steam (HPS) headers and produce either 15 psig or 60 psig steam at ' ~ 202~5~8 various times as shown in TABLE 1. This controls the effluent temperature from the condensers feeding CBA reac-tors during the different parts of the cycle to accomplish high sulfur recovery levels.
In TABLE 1, it can be seen that each of conden-sers Ca, Cb, and Cc of FIGURE 1 must undergo a high pres-sure to low pressure transition (indicated by brackets) at certain points in the cycle. At the time of the transi-tion, each such condenser is full of hot water in e~uilib-10 rium with high pressure steam at 60 psig. When the steam side of a condenser is switched to produce into the low pressure steam header, a large portion of this water tends to flash into steam which may overload the low pressure steam system. The pressure in the entire low pressure 15 steam system increases until the excess steam can be con-densed, sometimes taking several hours before the low pressure steam system returns to its normal operating pressure. This pressure surge causes the condensers con-nected together via the low pressure steam delivery system 20 not to provide the cooling required for feeding process gas at an optimum temperature to the CBA reactors. More-over, during the Precool period the reactor in the final position is the one which previously was operated as a "warm" CBA in the third position. The resulting rela-25 tively high temperature process gas being fed to the finalCBA reactor results in an increase in emissions from the plant since Claus conversion decreases with increasing temperature. This increase in emissions due to relatively high temperature process gas feeding the warm final CBA
~ 2~5~8 reactor continues, often for several hours until the con-denser approaches standard low pressure steam pressure long enough for the reactor in the final position to cool down to "cool" CBA operating conditions. Moreover, the 5 cool temperature wave moving through the catalytic reactor is slow and broad further delaying return to low emis-sions.
Thus, the problem addressed by this invention may be described as an emissions affecting pressure surge 10 in the low pressure steam system of the FIGURE 1 plant which results when a high pressure to low pressure transi-tion occurs on the steam side of a sulfur condenser and causes the condenser to fail to provide adequate cooling of process gas to a final CBA reactor.
Another aspect of the problem is that the pres-sure surge in the low pressure line may upset processes using the low pressure steam.
Another aspect of the problem is that the surge in the low pressure steam system can cause other conden-20 sers connected to the low pressure steam system to fail toprovide adequate cooling. Since the FIGURE 1 plant other-wise provides highly satisfactory performance (the use of three alternating Claus/CBA reactors provides the highest sulfur recovery of known extended Claus plants), it is 25 desirable to generally retain the plant's advantageous features, including production of high pressure and low pressure steam while solving this problem.
It is difficult to inexpensively solve this problem because of the large volume of steam generated by ~2~5~8 a sulfur condenser when the condenser is switched from operation at high pressure to operation at low pressure.
An auxiliary condenser can be added downstream of each of condensers Ca, Cb, and Cc to produce low pressure steam, 5 with process gas flowing through each auxiliary condenser only when lower effluent temperatures are required, and at other times, the process gas bypassing the auxiliary con-densers. Since condensers are=large and more expensive than reactors this represents a costly solution to the 10 problem.
An object of the invention is to provide an improved extended Claus plant and process of the type in which at least three Claus catalytic reactors are each periodically alternated between operation under high tem-15 perature Claus conditions and operation under cold bedadsorption conditions. A further object is such a process and plant which requires only four sulfur condensers instead of five as required by the FIGURE 1 plant. A fur-ther object is such a process and plant in which periodic 20 changes of sulfur condensers from operation as part of high pressure steam delivery system to operation as part of low pressure steam delivery system does not result in an increase in emissions from the sulfur plant; also, a process and plant which does not periodically upset the 25 low pressure steam system and thereby cause upsets in other processes connected to this steam system. Other objects and advantages will be apparent from the following description and the claims.
5 ~ 3 SUMMARY OF THE INVENTION
FIGURE 1 shows a prior art plant of the type in which at least three reactor/condenser units A, B, C are alternated between Claus and CBA conditions. The plant of 5 FIGURE 1 requires five sulfur condensers. This has been discovered to be the consequence of the prior art practice of rotating a reactor with the condenser following it through the cycle of operations in the FIGURE 1 plant.
Since the gas leaving a CBA reactor has a depressed dew-10 point, and since the final reactor in the FIGURE 1 plantis maintained at a minimal temperature with a minimal tem-perature rise across it, the dewpoint of the gas leaving the final reactor is well below the sulfur condenser effluent temperature and may even be below the sulfur sol-15 idification temperature. Therefore, sulfur present hasalready been removed by adsorption on catalyst in the final CBA reactor before the process gas enters the final condenser. Thus, no suifur can be condensed in the con-denser which follows the final CBA reactor and this con-20 denser is unnecessary. This is illustrated in TABLE 1 byinspecting the entries represented by a double asterisk.
According to an aspect of the invention, a con-denser preceding a reactor is rotated as a unit with the reactor as the unit is rotated through the cycle of oper-25 ations. Compared with the prior art plant of FIGURE 1 andTABLE 1, this saves the installation of one condenser along with, during operation, controlling that condenser to switch between LPS and HPS steam systems.
2 ~
Thus, a sulfur recovery plant comprises three or more switching units each comprising a Claus catalytic reactor which is periodically alternated between operation under effective high temperature Claus conditions and 5 operation under effective cold bed adsorption conditions.
Each switching unit comprises an inlet sulfur condenser having a gas inlet and a gas outlet and a valve bypass line connecting the gas inlet and the gas outlet of the sulfur condenser. A Claus catalytic reactor in the unit 10 has an inlet connected in flow communication with the gas outlet of the sulfur condenser and has a gas outlet.
Inlet means, selectably by valve control connects the inlet of the sulfur condenser in flow communication with a gas outlet of a Claus catalytic reactor of at least 15 another switching unit or with a source of process gas from which sulfur will be removed, optionally a high tem-perature Claus reactor. Outlet means, selectably by valve control, connects the gas outlet of the Claus catalytic reactor in flow communication with an inlet of one of at 20 least one other switching unit and a tail gas disposal line. Each inlet sulfur condenser is thus effective for selectably by valve control receiving gas from outlet means of another switching unit and each switching unit comprising a respective inlet sulfur condenser and a Claus 25 catalytic reactor downstream thereof is rotated as a unit in operation of the plant and alternates between operation under effective high temperature Claus conditions and under effective cold bed adsorption conditions.
2~26~4g In accordance with a further aspect of the invention, a high pressure to low pressure transition in the plant shown in FIGURE 1 is prevented from causing an increase in emissions in the invented plant. The invented 5 plant and process are provided with means for placing a sulfur condenser undergoing a high pressure to low pres-sure transition in a position feeding a reactor not requiring cold process feed such that the pressure transi-tion can be accomplished over a period of time effective 10 for not affecting cooling effectiveness of other conden-sers or steam users connected to low pressure system.
BRIEF DESCRIPTION OF THE DRAWINGS
EIGURE l illustrates an extended Claus process and plant in which at least three Claus catalytic reactors 15 are alternately periodically operated under high temper-ature Claus conditions and under cold bed adsorption con-ditions.
FIGURE 2 illustrates an improved plant and proc-ess in accordance with the invention which eliminates need 20 for one sulfur condenser of FIGURE 1.
FIGURE 3 illustrates an alternative embodiment of the plant of FIGURE 2 which prevents a high pressure to low pressure transition in a sulfur condenser from causing a pressure surge in the low pressure steam delivery system 25 which causes an increase in emissions from the plant.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIGURE 2, it can be seen that in comparison with the plant of FIGURE 1, each switching unit A, B, C has a inlet sulfur condenser Ca, Cb, Cc 2~54~
respectiveLy associated therewith which is upstream of the respective catalytic reactor Ra, Rb, Rc and that the con-denser preceding a reactor is rotated with the reactor through the sequence of operations.
Each inlet sulfur condenser is adapted with a valved bypass line 11 so as to provide bypass reheat gas for gas being fed to the reactor under Claus 2 operation, and correspondingly valve Vb has been eliminated. Also, only four sulfur condensers are required since a condenser lO no longer occurs downstream of a final catalytic reactor in any of the modes of operation. Thus, the addition of two additional valved bypass lines and a new configuration of pipes and vessels has permitted the elimination of a sulfur condenser. Since a sulfur condenser is often phys-15 ically large and more expensive than a catalytic reactor,substantial savings results.
Referring now to TABLE 2, TABLE 2 illustrates operation sequence and steam production from the FIGURE 2 plant. As can be seen by comparing TABLE 1 and TABLE 2, 20 the entries indicated in TABLE 1 by a double asterisk have been eliminated from the operation of the plant in accord-ance with FIGURE 2 and TABLE 2. The steam production from the FIGURE 2 plant, however, is substantially the same as steam production in the FIGURE 1 plant (except that steam 25 production from tail gas has been eliminated).
However, eVen though the FIGURE 2 plant elimi-nates the need for one sulfur condenser relative to the FIGURE 1 plant, it does not eliminate the emissions 2026~8 ,c s ~ C
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affecting pressure surge occurring at points in the cycle.
This can be seen from the following discussion.
In the FIGURE 1 plant, at the end of the Heat Soak Period the reactor in the second position is hot and 5 fully regenerated, the reactor in the third position is on adsorption as a "warm" CBA reactor (feed temperature 280~-300~F or warmer), and the reactor in the final posi-tion is on adsorption as a ~Icool~l CBA reactor (feed tem-perature 260~-280~F). The hot Claus catalyst in the 10 second position reactor must be cooled prior to switching the reactor to the final position as overall sulfur recov-ery is largely a function of the temperature of that por-tion of catalyst within the final reactor in which Claus reaction occurs. During Precool, therefore, the hot newly 15 regenerated catalyst is placed in the third position for a limited period of time for cooling. At the same time, the llwarmll CBA reactor which had been in the third position is switched to the final position, and the cool CBA reactor which had been in the final position is switched to the 20 second position (for example, Mode C). High emissions will result in this period if the warm reactor in the final position is maintained warm. It must be cooled to llcoolll CBA operating conditions to keep the sulfur emis-sions at a minimum. During Precool, however, the conden-25 ser feeding the reactor in the final position is the onewhich was making high pressure steam during the previous Heat Soak period when it fed gas to the same reactor in the third (llwarmll CBA) position. To keep emissions at a minimum, at the beginning of the Precool period, this con-2~2$~48 denser must very quickly be switched to low pressuresteam. Prior to switching, the hot water in this conden-ser is in e~uilibrium with steam at the higher pressure.
Reducing the pressure in this condenser causes a signif-5 icant fraction of this water to flash to steam at thelower pressure in order to maintain the thermodynamic equilibrium. The amount of steam thus produced is nearly independent of the rate at which the pressure in the vessel is reduced. If the condenser is suddenly connected 10 to the low pressure steam header, the total amount of steam that would be produced from the hot water will be produced very quickly, and the steam rate produced into the low pressure steam header will be very large. In fact, it may well be so large that the users of low pres-15 sure steam on this header cannot use the steam fast enoughand the pressure within the header will increase. A new thermodynamic equilibrium will be reached as the switch is made from an isolated hot high pressure condenser and a low pressure steam header to a combined system with the 20 condenser connected to the steam header. A higher pres-sure in the low pressure steam header means the temper-ature of the steam within it will also increase. This means that the condenser being switched and the other con-densers producing steam into this header will do a less 25 efficient job of cooling and those pieces of equipment which use the low pressure steam will suddenly receive a hotter steam which may result in upsets of the control' system. A solution would be to very slowly bleed pressure from the condenser being switched from high pressure to 2B265~
low pressure operation into the low pressure steam headerat such a rate that the amount of additional steam going into it from the reduction of the pressure on the hot water is insufficient to increase the pressure within the 5 steam header. However, if this is done for the FIGURE 1 plant, the gas feeding the final CBA reactor is too warm and a period of high sulfur emissions results.
Referring now to FIGURE 2, it can be seen that the FIGURE 2 plant is constrained by its piping and is 10 unable when in mode A to interchange, for example, units A
and B while keeping unit C in final position; or when in mode B, is unable to interchange units B and C while keep-ing unit A in final position; or when in mode C, is unable to interchange units A and C while keeping unit B in final 15 position.
The consequences of this can be illustrated by considering, as in FIGURE 2, a Claus reactor Rv followed by Claus/CBA reactors, Ra, Rb, Rc which are each preceded by a condenser Ca, Cb, and Cc and which are piped so that 20 each reactor and condenser (Ca and Ra, Cb and Rb, and Cc and Rc) rotate as a unit in sequences illustrated by TABLE 2. During the heat soak period, the sequence is Rv, Ca (bypassed), Ra, Cb (60 psig), Rb, Cc (15 psig), Rc.
This allows Ra to be heated for the heat soak period of 25 regeneration, Cb to make higher pressure steam, Rb to be a CBA reactor operated slightly warmer than the final CBA
reactor, and Cc to cool a gas as much as possible for a higher recovery in final CBA reactor Rc.
2~6~
When switching to the precool period, the sequence becomes Rv, Cc (15 psig steam), Rc, Ca (15 psig steam), Ra, Cb (15 psig steam), Rb. Condenser Cc should make 15 psig steam to keep temperatures low in Rc which 5 will cause more Claus reaction to occur and therefore less reaction and heat of reaction in the following CBA reactor Ra which allows it to cool more quickly. Also, in the steps preceding Precool, condenser Cc had been making 15 psig steam, so maintaining it at 15 psig is causes prob-10 lem. Condenser Ca produces 15 psig steam since it is fur-nishing the cool gas to do the cooling of Ra. A higher pressure of steam in the low pressure steam system result-ing from connecting the shell side of Cb into the LPS
system would prevent the reactor Ra from becoming as cool 15 and then in the next step, Ra will be placed in the final position and the recovery of the process, which is a strong function of the temperature of the final adsorption reactor, will be affected. Condenser Cb is now sending process gas to the reactor Rb in the final position. In 20 the previous step, this condenser produced 60 psig steam, and the reactor following it Rb is therefore warmer than optimum. This reactor Rb is now in the final position and must be further cooled to maintain a high sulfur recovery (as explained above). To do this, condenser Cb must now 25 produce 15 psig steam. Therefore, the need for a sudden reduction in a condenser steam pressure still exists in this configuration, and the corresponding pressure surge in the low pressure steam system will occur.
2~2~48 Thus, whereas the FIGURE 2 plant eliminates the need for one of the sulfur condensers of the FIGURE 1 plant, the FIGURE 2 plant continues to have an emissions affecting surge in the low pressure steam system.
However, by addition of valved lines 12 (con-necting unit A to inlet of unit C, unit B to inlet of unit A, and unit C to inlet of unit B - see reference numerals 2'A, 2'B, 2'C indicating such connections) as shown on FIGURE 3, reactor effluent from A can be fed to either of 10 units B or C; from B can be fed to either of units A or C;
and from C can be fed to either of units A or B, permit-ting operation in accordance with the invention.
Referring now to TABLE 3, it can be seen that the need for a sudden 60 to 15 psi transition has been 15 eliminated. During the heat soak period ~see Mode A), the sequence is Rv, Ca (bypassed), Ra, Cb (60 psig), Rb, Cc (15 psig), Rc. This allows Ra to be heated for the heat soak period of regeneration, Cb to make higher pressure steam, Rb to be a "warm" CBA reactor, and Cc to cool a gas 20 sufficiently for a "cool" CBA reactor Rc for maximum recovery.
When switching to the precool period, the sequence becomes Rv, Cb (60 psig), Rb, Ca (15 psig), Ra, Cc (15 psig)~ Rc While 15 psig steam could be produced in Conden-ser Cb to provide a lower feed temperature to Rb to maxi-mize the Claus reaction in it, and thereby reduce the heat of reaction in cooling reactor Ra, it is not practical in this configuration. In the steps preceding Precool, con-; ~ - 2026~48 ., -n 3 c c J
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_ uc~rr~ v-o ¢~C c~c~c,~c~ ,~,~,~,~ ~ ~Jc~lCu r ~ ~ r~ c -18a-2026~8 denser Cb was making 60 psig steam as it was feeding the warm CBA reactor on adsorption. The reaction differential in reactor Ra due to the difference in steam pressure in Cb can be compensated for by slightly increasing the Pre-5 cool time period. Condenser Ca will make 15 psig steam tocool as quickly as possible the newly regenerated reactor Ra. In the steps prior to Precool, condenser Cc was making 15 psig steam and feeding cool gas to cool final CBA reactor Rc. It can continue to do this during Precool 10 and a cool reactor is maintained in the final position with a cool feed without the need for a sudden high pres-sure to low pressure transition to occur on the steam side of a condenser with the corresponding sulfur emission affecting pressure surge within the low pressure steam 15 system.
With this invention, when the steam pressure in a condenser must be reduced (See Table 3, when a condenser is bypassed during the Heat-up, Plateau, and Heat Soak periods), a relatively long time lasting several periods 20 (approximately 3 to 6 hours or more) is allowed for the high pressure in the condenser to be bled into the low steam pressure header without causing a sulfur emissions affection pressure surge within the low pressure steam header.
The invention is directed to solution of a par-ticular problem in a particular type of extended Claus sulfur recovery plant. The plant is one in which three reactor/condenser units are alternated between Claus and CBA operation, in which the steam production side of a 1~ 2026548 condenser periodically undergoes a high pressure to low pressure transition, in which such transition affects recovery due to temperature effects within the low pres-sure steam system resulting in other condensers which are 5 tied on shell side via a low pressure steam delivery system to the condenser undergoing the transition; and to a plant which produces both high pressure and low pressure steam. The invention in its various aspects eliminates the need for one of the sulfur condensers in a prior art 10 design and permits retaining the capabilities of this plant in maximized production of high pressure and low pressure steam while avoiding increases in emissions which result from the high pressure to low pressure transition.
The invention has been described in terms of 15 specific and preferred embodiments, but is not limited thereto but by the following claims interpreted according to applicable principles of law.
Pendergraft, P. T.
CONDENSER-REACTOR SWITCHING UNITS FOR
EXTENDED CLAUS PROCESS
FIELD OF THE INVENTION
The invention relates to extended Claus sulfur recovery plants and processes of the type having at least three reactors each periodically operated alternately under high temperature Claus and under CBA conditions and 15 particularly to reactor switching units for such plants.
In another particular aspect, the invention relates to such plants and processes which require fewer sulfur con-densers than a prior art design. In another particular aspect, the invention relates to such plants and processes 20 which prevent a high pressure to low pressure transition in a condenser from affecting emissions from the sulfur plant.
SETTING OF THE INVENTION
An extended Claus sulfur recovery plant com-prises one or more catalytic reactors operated under high temperature Claus conditions in series with one or more catalytic reactors operated under cold bed adsorption (CBA) conditions. Under high temperature Claus condi-2 0 2 6 ~i ~ 8 tions, sulfur formed in presence of Claus catalyst is con-tinuously removed from the reactor in vapor phase and condensed in a sulfur condenser. Under CBA conditions, most sulfur formed is deposited and accumulated on the 5 Claus catalyst. The sulfur is periodically removed during regeneration by effective high temperature gas flowing through the reactor and vaporizing sulfur which is with-drawn in vapor phase from the reactor and condensed in a sulfur condenser. High temperature Claus operation and 10 regeneration can occur concurrently.
Besides condensing sulfur, shell-and-tube indi-rect heat exchangers used as sulfur condensers produce useful steam. In such shell-and-tube exchangers, boiler feed water in the shell side is converted to steam while 15 in the tube side process gas containing sulfur vapor is cooled and sulfur is condensed and removed. For purposes of discussion, steam production on the shell side and gas cooling and sulfur condensation on the tube side is assumed. However, steam production on the tube side and 20 process gas cooling and sulfur condensation on the shell side can also be used.
Where the process gas after cooling is above about 300~F, high pressure (for example, 60 psig) steam can be produced. When the process gas after cooling is 25 below about 300~F down to about 260~F, only low pressure steam (for example, 15 psig) can be produced. High pres-sure steam has many uses in plants and represents signif-icant economic advantage relative to low pressure steam which has fewer applications. It is desirable to maximize 2~2~
high pressure steam production and to produce low pressure steam only when high pressure steam cannot be produced consistent with efficient and cost effective design and operation of the sulfur plant.
In extended Claus processes, sulfur condensers cooling gas for introduction into CBA reactors typically operated at temperatures less than 300~F generally produce only low pressure steam whereas sulfur condensers feeding high temperature Claus reactors or ~Iwarm~l CBA reactors can 10 be used to produce high pressure steam. When a reactor is alternated between llwarmll and llcoolll CBA and high temper-ature Claus operations concurrent with regeneration, a condenser feeding that reactor sometimes produces low pressure steam and sometimes produces high pressure steam.
In the type of extended Claus sulfur recovery plant in which three or more reactors are each period-ically alternated between CBA and high temperature Claus conditions, conventional plant design associates a sulfur condenser with a reactor and rotates the reactor/condenser 20 pair as a unit. Such a plant is shown in FIGURE 1 - PRIOR
ART. TABLE A identifies reference numerals in FIGURE 1 for easy identification.
' ~26~
t - TABLE A
Symbol Refers To FURN/WHB Claus furnace (FURN) with waste heat boiler (WHB) CF Furnace sulfur condenser Va WHB bypass reheat valve Rv Claus reactor (dedicated to high temperature Claus operation) Cv Claus reactor condenser Vb Claus reactor condenser bypass reheat valve A Claus/CBA Reactor Unit A
B Claus/CBA Reactor Unit B
15 C Claus/CBA Reactor Unit C
1,1' Process gas supply to reactor from unit Cv or another reactor or reactor unit 2 Alternate process ~as supply to reactor unit from another reactor unit 20 3 Reactor effluent line 4 Condenser effluent line Effluent line to another reactor unit 6 Effluent line to tail gas (TG) disposal 7 High pressure steam (HPS) line 25 8,8' Low pressure steam (LPS) line 9 Liquid sulfur (S) outlet ~oiler feedwater (BFW) line 13 Timer/controller for valves ~02~548 TABLE 1 shows steam production and operation sequences for operation of the FIGURE 1 plant. In the FIGURE 1 plant, reactor Rv is operated only as a first Claus reactor ("Claus l") while reactors Ra, Rb, Rc alter-5 nate hetween CBA operation and Claus operation. (Note: A
~eactor operated under high temperature Claus conditions may be referred to as a Claus reactor; likewise, a reactor operated under CBA conditions may be referred to as a CBA
reactor - both Claus and CBA reactors catalyze the Claus 10 reaction.) A reactor previously operated under CBA condi-tions which is being regenerated in the second position also operates as a second Claus reactor ("Claus 2"). CBA
operation in the FIIJURE l plant occurs when a reactor is in the third and fourth positions. The third position 15 reactor, after precooling to CBA operation conditions, is generally operated as a "warm" CBA (feed temperature above 280-300~F or more) and the fourth position reactor is gen-erally operated as à "cool" CBA reactor (feed temperature about 250-260~F) for maximum recovery. Regeneration in 20 the second position concurrently with Claus 2 operation includes heatup, plateau, and heat soak as is known to those skilled in the art (see U.S. Patents 4,482,532, B. E. Cabanaw, issued November 13, 1984 and 4,822,591, R. L. Reed, J. W. Palm, issued April 18, 1989) Precooling of a newly regenerated reactor is accomplished prior to returning a reactor to CBA operation. These steps individually are well known to those skilled in the art, and from FIGURE 1 .. ~ L
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and TABLE 1 those skilled in the art will fully understand the se~uence of operation.
One problem with the FIGURE 1 plant is that in each of the modes of operation, there is always a conden-5 ser following the final CBA reactor. The gas leaving thisreactor is normally cool (less than 280~F) with a sulfur dewpoint depression of 50 to 80~F. Therefore, no sulfur will condense from this gas above the sulfur freezing point of about 235~F. Running this gas through a conden-10 ser just cools it with no benefit (except, perhaps, thesmall amount of steam which would be produced) and with the detriment that more fuel gas will be re~uired in the incinerator to dispose of the cooled tail gas.
Another problem with the FIGURE 1 plant arises 15 from the practice of switching a condenser from a high pressure environment to a low pressure environment during certain portions of the operating cycle. This practice periodically overloads the low pressure steam delivery system resulting in an increase in emissions from the 20 plant. This problem is discussed below in more detail.
A preferred precooling method for the FIGURE l plant is a "backstep," such as precooling in mode C fol-lowing regeneration in Mode A and prior to switching to Mode B, as this method does not preload with sulfur a 25 freshly regenerated reactor before it is placed under CBA
conditions.
The three condensers Ca, Cb, Cc are tied to both low pressure steam (LPS) and high pressure steam (HPS) headers and produce either 15 psig or 60 psig steam at ' ~ 202~5~8 various times as shown in TABLE 1. This controls the effluent temperature from the condensers feeding CBA reac-tors during the different parts of the cycle to accomplish high sulfur recovery levels.
In TABLE 1, it can be seen that each of conden-sers Ca, Cb, and Cc of FIGURE 1 must undergo a high pres-sure to low pressure transition (indicated by brackets) at certain points in the cycle. At the time of the transi-tion, each such condenser is full of hot water in e~uilib-10 rium with high pressure steam at 60 psig. When the steam side of a condenser is switched to produce into the low pressure steam header, a large portion of this water tends to flash into steam which may overload the low pressure steam system. The pressure in the entire low pressure 15 steam system increases until the excess steam can be con-densed, sometimes taking several hours before the low pressure steam system returns to its normal operating pressure. This pressure surge causes the condensers con-nected together via the low pressure steam delivery system 20 not to provide the cooling required for feeding process gas at an optimum temperature to the CBA reactors. More-over, during the Precool period the reactor in the final position is the one which previously was operated as a "warm" CBA in the third position. The resulting rela-25 tively high temperature process gas being fed to the finalCBA reactor results in an increase in emissions from the plant since Claus conversion decreases with increasing temperature. This increase in emissions due to relatively high temperature process gas feeding the warm final CBA
~ 2~5~8 reactor continues, often for several hours until the con-denser approaches standard low pressure steam pressure long enough for the reactor in the final position to cool down to "cool" CBA operating conditions. Moreover, the 5 cool temperature wave moving through the catalytic reactor is slow and broad further delaying return to low emis-sions.
Thus, the problem addressed by this invention may be described as an emissions affecting pressure surge 10 in the low pressure steam system of the FIGURE 1 plant which results when a high pressure to low pressure transi-tion occurs on the steam side of a sulfur condenser and causes the condenser to fail to provide adequate cooling of process gas to a final CBA reactor.
Another aspect of the problem is that the pres-sure surge in the low pressure line may upset processes using the low pressure steam.
Another aspect of the problem is that the surge in the low pressure steam system can cause other conden-20 sers connected to the low pressure steam system to fail toprovide adequate cooling. Since the FIGURE 1 plant other-wise provides highly satisfactory performance (the use of three alternating Claus/CBA reactors provides the highest sulfur recovery of known extended Claus plants), it is 25 desirable to generally retain the plant's advantageous features, including production of high pressure and low pressure steam while solving this problem.
It is difficult to inexpensively solve this problem because of the large volume of steam generated by ~2~5~8 a sulfur condenser when the condenser is switched from operation at high pressure to operation at low pressure.
An auxiliary condenser can be added downstream of each of condensers Ca, Cb, and Cc to produce low pressure steam, 5 with process gas flowing through each auxiliary condenser only when lower effluent temperatures are required, and at other times, the process gas bypassing the auxiliary con-densers. Since condensers are=large and more expensive than reactors this represents a costly solution to the 10 problem.
An object of the invention is to provide an improved extended Claus plant and process of the type in which at least three Claus catalytic reactors are each periodically alternated between operation under high tem-15 perature Claus conditions and operation under cold bedadsorption conditions. A further object is such a process and plant which requires only four sulfur condensers instead of five as required by the FIGURE 1 plant. A fur-ther object is such a process and plant in which periodic 20 changes of sulfur condensers from operation as part of high pressure steam delivery system to operation as part of low pressure steam delivery system does not result in an increase in emissions from the sulfur plant; also, a process and plant which does not periodically upset the 25 low pressure steam system and thereby cause upsets in other processes connected to this steam system. Other objects and advantages will be apparent from the following description and the claims.
5 ~ 3 SUMMARY OF THE INVENTION
FIGURE 1 shows a prior art plant of the type in which at least three reactor/condenser units A, B, C are alternated between Claus and CBA conditions. The plant of 5 FIGURE 1 requires five sulfur condensers. This has been discovered to be the consequence of the prior art practice of rotating a reactor with the condenser following it through the cycle of operations in the FIGURE 1 plant.
Since the gas leaving a CBA reactor has a depressed dew-10 point, and since the final reactor in the FIGURE 1 plantis maintained at a minimal temperature with a minimal tem-perature rise across it, the dewpoint of the gas leaving the final reactor is well below the sulfur condenser effluent temperature and may even be below the sulfur sol-15 idification temperature. Therefore, sulfur present hasalready been removed by adsorption on catalyst in the final CBA reactor before the process gas enters the final condenser. Thus, no suifur can be condensed in the con-denser which follows the final CBA reactor and this con-20 denser is unnecessary. This is illustrated in TABLE 1 byinspecting the entries represented by a double asterisk.
According to an aspect of the invention, a con-denser preceding a reactor is rotated as a unit with the reactor as the unit is rotated through the cycle of oper-25 ations. Compared with the prior art plant of FIGURE 1 andTABLE 1, this saves the installation of one condenser along with, during operation, controlling that condenser to switch between LPS and HPS steam systems.
2 ~
Thus, a sulfur recovery plant comprises three or more switching units each comprising a Claus catalytic reactor which is periodically alternated between operation under effective high temperature Claus conditions and 5 operation under effective cold bed adsorption conditions.
Each switching unit comprises an inlet sulfur condenser having a gas inlet and a gas outlet and a valve bypass line connecting the gas inlet and the gas outlet of the sulfur condenser. A Claus catalytic reactor in the unit 10 has an inlet connected in flow communication with the gas outlet of the sulfur condenser and has a gas outlet.
Inlet means, selectably by valve control connects the inlet of the sulfur condenser in flow communication with a gas outlet of a Claus catalytic reactor of at least 15 another switching unit or with a source of process gas from which sulfur will be removed, optionally a high tem-perature Claus reactor. Outlet means, selectably by valve control, connects the gas outlet of the Claus catalytic reactor in flow communication with an inlet of one of at 20 least one other switching unit and a tail gas disposal line. Each inlet sulfur condenser is thus effective for selectably by valve control receiving gas from outlet means of another switching unit and each switching unit comprising a respective inlet sulfur condenser and a Claus 25 catalytic reactor downstream thereof is rotated as a unit in operation of the plant and alternates between operation under effective high temperature Claus conditions and under effective cold bed adsorption conditions.
2~26~4g In accordance with a further aspect of the invention, a high pressure to low pressure transition in the plant shown in FIGURE 1 is prevented from causing an increase in emissions in the invented plant. The invented 5 plant and process are provided with means for placing a sulfur condenser undergoing a high pressure to low pres-sure transition in a position feeding a reactor not requiring cold process feed such that the pressure transi-tion can be accomplished over a period of time effective 10 for not affecting cooling effectiveness of other conden-sers or steam users connected to low pressure system.
BRIEF DESCRIPTION OF THE DRAWINGS
EIGURE l illustrates an extended Claus process and plant in which at least three Claus catalytic reactors 15 are alternately periodically operated under high temper-ature Claus conditions and under cold bed adsorption con-ditions.
FIGURE 2 illustrates an improved plant and proc-ess in accordance with the invention which eliminates need 20 for one sulfur condenser of FIGURE 1.
FIGURE 3 illustrates an alternative embodiment of the plant of FIGURE 2 which prevents a high pressure to low pressure transition in a sulfur condenser from causing a pressure surge in the low pressure steam delivery system 25 which causes an increase in emissions from the plant.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIGURE 2, it can be seen that in comparison with the plant of FIGURE 1, each switching unit A, B, C has a inlet sulfur condenser Ca, Cb, Cc 2~54~
respectiveLy associated therewith which is upstream of the respective catalytic reactor Ra, Rb, Rc and that the con-denser preceding a reactor is rotated with the reactor through the sequence of operations.
Each inlet sulfur condenser is adapted with a valved bypass line 11 so as to provide bypass reheat gas for gas being fed to the reactor under Claus 2 operation, and correspondingly valve Vb has been eliminated. Also, only four sulfur condensers are required since a condenser lO no longer occurs downstream of a final catalytic reactor in any of the modes of operation. Thus, the addition of two additional valved bypass lines and a new configuration of pipes and vessels has permitted the elimination of a sulfur condenser. Since a sulfur condenser is often phys-15 ically large and more expensive than a catalytic reactor,substantial savings results.
Referring now to TABLE 2, TABLE 2 illustrates operation sequence and steam production from the FIGURE 2 plant. As can be seen by comparing TABLE 1 and TABLE 2, 20 the entries indicated in TABLE 1 by a double asterisk have been eliminated from the operation of the plant in accord-ance with FIGURE 2 and TABLE 2. The steam production from the FIGURE 2 plant, however, is substantially the same as steam production in the FIGURE 1 plant (except that steam 25 production from tail gas has been eliminated).
However, eVen though the FIGURE 2 plant elimi-nates the need for one sulfur condenser relative to the FIGURE 1 plant, it does not eliminate the emissions 2026~8 ,c s ~ C
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affecting pressure surge occurring at points in the cycle.
This can be seen from the following discussion.
In the FIGURE 1 plant, at the end of the Heat Soak Period the reactor in the second position is hot and 5 fully regenerated, the reactor in the third position is on adsorption as a "warm" CBA reactor (feed temperature 280~-300~F or warmer), and the reactor in the final posi-tion is on adsorption as a ~Icool~l CBA reactor (feed tem-perature 260~-280~F). The hot Claus catalyst in the 10 second position reactor must be cooled prior to switching the reactor to the final position as overall sulfur recov-ery is largely a function of the temperature of that por-tion of catalyst within the final reactor in which Claus reaction occurs. During Precool, therefore, the hot newly 15 regenerated catalyst is placed in the third position for a limited period of time for cooling. At the same time, the llwarmll CBA reactor which had been in the third position is switched to the final position, and the cool CBA reactor which had been in the final position is switched to the 20 second position (for example, Mode C). High emissions will result in this period if the warm reactor in the final position is maintained warm. It must be cooled to llcoolll CBA operating conditions to keep the sulfur emis-sions at a minimum. During Precool, however, the conden-25 ser feeding the reactor in the final position is the onewhich was making high pressure steam during the previous Heat Soak period when it fed gas to the same reactor in the third (llwarmll CBA) position. To keep emissions at a minimum, at the beginning of the Precool period, this con-2~2$~48 denser must very quickly be switched to low pressuresteam. Prior to switching, the hot water in this conden-ser is in e~uilibrium with steam at the higher pressure.
Reducing the pressure in this condenser causes a signif-5 icant fraction of this water to flash to steam at thelower pressure in order to maintain the thermodynamic equilibrium. The amount of steam thus produced is nearly independent of the rate at which the pressure in the vessel is reduced. If the condenser is suddenly connected 10 to the low pressure steam header, the total amount of steam that would be produced from the hot water will be produced very quickly, and the steam rate produced into the low pressure steam header will be very large. In fact, it may well be so large that the users of low pres-15 sure steam on this header cannot use the steam fast enoughand the pressure within the header will increase. A new thermodynamic equilibrium will be reached as the switch is made from an isolated hot high pressure condenser and a low pressure steam header to a combined system with the 20 condenser connected to the steam header. A higher pres-sure in the low pressure steam header means the temper-ature of the steam within it will also increase. This means that the condenser being switched and the other con-densers producing steam into this header will do a less 25 efficient job of cooling and those pieces of equipment which use the low pressure steam will suddenly receive a hotter steam which may result in upsets of the control' system. A solution would be to very slowly bleed pressure from the condenser being switched from high pressure to 2B265~
low pressure operation into the low pressure steam headerat such a rate that the amount of additional steam going into it from the reduction of the pressure on the hot water is insufficient to increase the pressure within the 5 steam header. However, if this is done for the FIGURE 1 plant, the gas feeding the final CBA reactor is too warm and a period of high sulfur emissions results.
Referring now to FIGURE 2, it can be seen that the FIGURE 2 plant is constrained by its piping and is 10 unable when in mode A to interchange, for example, units A
and B while keeping unit C in final position; or when in mode B, is unable to interchange units B and C while keep-ing unit A in final position; or when in mode C, is unable to interchange units A and C while keeping unit B in final 15 position.
The consequences of this can be illustrated by considering, as in FIGURE 2, a Claus reactor Rv followed by Claus/CBA reactors, Ra, Rb, Rc which are each preceded by a condenser Ca, Cb, and Cc and which are piped so that 20 each reactor and condenser (Ca and Ra, Cb and Rb, and Cc and Rc) rotate as a unit in sequences illustrated by TABLE 2. During the heat soak period, the sequence is Rv, Ca (bypassed), Ra, Cb (60 psig), Rb, Cc (15 psig), Rc.
This allows Ra to be heated for the heat soak period of 25 regeneration, Cb to make higher pressure steam, Rb to be a CBA reactor operated slightly warmer than the final CBA
reactor, and Cc to cool a gas as much as possible for a higher recovery in final CBA reactor Rc.
2~6~
When switching to the precool period, the sequence becomes Rv, Cc (15 psig steam), Rc, Ca (15 psig steam), Ra, Cb (15 psig steam), Rb. Condenser Cc should make 15 psig steam to keep temperatures low in Rc which 5 will cause more Claus reaction to occur and therefore less reaction and heat of reaction in the following CBA reactor Ra which allows it to cool more quickly. Also, in the steps preceding Precool, condenser Cc had been making 15 psig steam, so maintaining it at 15 psig is causes prob-10 lem. Condenser Ca produces 15 psig steam since it is fur-nishing the cool gas to do the cooling of Ra. A higher pressure of steam in the low pressure steam system result-ing from connecting the shell side of Cb into the LPS
system would prevent the reactor Ra from becoming as cool 15 and then in the next step, Ra will be placed in the final position and the recovery of the process, which is a strong function of the temperature of the final adsorption reactor, will be affected. Condenser Cb is now sending process gas to the reactor Rb in the final position. In 20 the previous step, this condenser produced 60 psig steam, and the reactor following it Rb is therefore warmer than optimum. This reactor Rb is now in the final position and must be further cooled to maintain a high sulfur recovery (as explained above). To do this, condenser Cb must now 25 produce 15 psig steam. Therefore, the need for a sudden reduction in a condenser steam pressure still exists in this configuration, and the corresponding pressure surge in the low pressure steam system will occur.
2~2~48 Thus, whereas the FIGURE 2 plant eliminates the need for one of the sulfur condensers of the FIGURE 1 plant, the FIGURE 2 plant continues to have an emissions affecting surge in the low pressure steam system.
However, by addition of valved lines 12 (con-necting unit A to inlet of unit C, unit B to inlet of unit A, and unit C to inlet of unit B - see reference numerals 2'A, 2'B, 2'C indicating such connections) as shown on FIGURE 3, reactor effluent from A can be fed to either of 10 units B or C; from B can be fed to either of units A or C;
and from C can be fed to either of units A or B, permit-ting operation in accordance with the invention.
Referring now to TABLE 3, it can be seen that the need for a sudden 60 to 15 psi transition has been 15 eliminated. During the heat soak period ~see Mode A), the sequence is Rv, Ca (bypassed), Ra, Cb (60 psig), Rb, Cc (15 psig), Rc. This allows Ra to be heated for the heat soak period of regeneration, Cb to make higher pressure steam, Rb to be a "warm" CBA reactor, and Cc to cool a gas 20 sufficiently for a "cool" CBA reactor Rc for maximum recovery.
When switching to the precool period, the sequence becomes Rv, Cb (60 psig), Rb, Ca (15 psig), Ra, Cc (15 psig)~ Rc While 15 psig steam could be produced in Conden-ser Cb to provide a lower feed temperature to Rb to maxi-mize the Claus reaction in it, and thereby reduce the heat of reaction in cooling reactor Ra, it is not practical in this configuration. In the steps preceding Precool, con-; ~ - 2026~48 ., -n 3 c c J
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_ uc~rr~ v-o ¢~C c~c~c,~c~ ,~,~,~,~ ~ ~Jc~lCu r ~ ~ r~ c -18a-2026~8 denser Cb was making 60 psig steam as it was feeding the warm CBA reactor on adsorption. The reaction differential in reactor Ra due to the difference in steam pressure in Cb can be compensated for by slightly increasing the Pre-5 cool time period. Condenser Ca will make 15 psig steam tocool as quickly as possible the newly regenerated reactor Ra. In the steps prior to Precool, condenser Cc was making 15 psig steam and feeding cool gas to cool final CBA reactor Rc. It can continue to do this during Precool 10 and a cool reactor is maintained in the final position with a cool feed without the need for a sudden high pres-sure to low pressure transition to occur on the steam side of a condenser with the corresponding sulfur emission affecting pressure surge within the low pressure steam 15 system.
With this invention, when the steam pressure in a condenser must be reduced (See Table 3, when a condenser is bypassed during the Heat-up, Plateau, and Heat Soak periods), a relatively long time lasting several periods 20 (approximately 3 to 6 hours or more) is allowed for the high pressure in the condenser to be bled into the low steam pressure header without causing a sulfur emissions affection pressure surge within the low pressure steam header.
The invention is directed to solution of a par-ticular problem in a particular type of extended Claus sulfur recovery plant. The plant is one in which three reactor/condenser units are alternated between Claus and CBA operation, in which the steam production side of a 1~ 2026548 condenser periodically undergoes a high pressure to low pressure transition, in which such transition affects recovery due to temperature effects within the low pres-sure steam system resulting in other condensers which are 5 tied on shell side via a low pressure steam delivery system to the condenser undergoing the transition; and to a plant which produces both high pressure and low pressure steam. The invention in its various aspects eliminates the need for one of the sulfur condensers in a prior art 10 design and permits retaining the capabilities of this plant in maximized production of high pressure and low pressure steam while avoiding increases in emissions which result from the high pressure to low pressure transition.
The invention has been described in terms of 15 specific and preferred embodiments, but is not limited thereto but by the following claims interpreted according to applicable principles of law.
Claims (10)
1. A sulfur recovery plant comprising:
at least three units connectable for sequentially receiving process gas and for removing sulfur therefrom, each unit having a Claus catalytic reactor alternately periodically operated under effective high temperature Claus conditions and periodically operated under effective cold bed adsorption conditions, each unit comprising:
a sulfur condenser having a gas inlet and a gas outlet;
the gas inlet being connectable by valve control in flow communication for receiving effluent process gas from one of a Claus catalytic reactor of another unit and a source of process gas from which sulfur is to be removed;
a valved bypass line connecting the gas inlet of the sulfur condenser with the gas outlet of the sulfur condenser;
the Claus catalytic reactor of each unit having an inlet connected in flow communication with the gas outlet of the sulfur condenser and having an effluent outlet;
outlet means for connecting the effluent outlet of the Claus catalytic reactor in flow communication with one of an inlet of at least one other unit and a tail gas line;
means for switching each inlet sulfur condenser as a unit with a downstream reactor during operation of the plant.
at least three units connectable for sequentially receiving process gas and for removing sulfur therefrom, each unit having a Claus catalytic reactor alternately periodically operated under effective high temperature Claus conditions and periodically operated under effective cold bed adsorption conditions, each unit comprising:
a sulfur condenser having a gas inlet and a gas outlet;
the gas inlet being connectable by valve control in flow communication for receiving effluent process gas from one of a Claus catalytic reactor of another unit and a source of process gas from which sulfur is to be removed;
a valved bypass line connecting the gas inlet of the sulfur condenser with the gas outlet of the sulfur condenser;
the Claus catalytic reactor of each unit having an inlet connected in flow communication with the gas outlet of the sulfur condenser and having an effluent outlet;
outlet means for connecting the effluent outlet of the Claus catalytic reactor in flow communication with one of an inlet of at least one other unit and a tail gas line;
means for switching each inlet sulfur condenser as a unit with a downstream reactor during operation of the plant.
2. The sulfur recovery plant of Claim 1 wherein the plant consists essentially of a Claus furnace and associated waste heat boiler, an furnace sulfur condenser, a first Claus high temperature catalytic reactor, three of said units, and piping and valves for connecting such for the recovery of sulfur.
3. The sulfur recovery plant of Claim 1 further comprising:
a first valved steam pressure line for receiving steam from inlet sulfur condensers of switching units and for delivering such steam to a first pressure steam delivery system;
a second valved steam pressure line for receiving steam from inlet sulfur condensers of switching units and for delivering such steam to a second pressure steam delivery system, the second pressure steam delivery system being at a lower pressure than the first pressure steam delivery system;
means for controlling first and second steam pressure lines for causing an inlet sulfur condenser of each unit periodically to undergo a high pressure to low pressure transition in the steam side thereof.
a first valved steam pressure line for receiving steam from inlet sulfur condensers of switching units and for delivering such steam to a first pressure steam delivery system;
a second valved steam pressure line for receiving steam from inlet sulfur condensers of switching units and for delivering such steam to a second pressure steam delivery system, the second pressure steam delivery system being at a lower pressure than the first pressure steam delivery system;
means for controlling first and second steam pressure lines for causing an inlet sulfur condenser of each unit periodically to undergo a high pressure to low pressure transition in the steam side thereof.
4. The plant of Claim 3 further comprising:
means for placing each condenser during such transition in a position where the transition can be accomplished at a rate effective for preventing such transition from causing an emissions affecting pressure surge in the second steam delivery system.
means for placing each condenser during such transition in a position where the transition can be accomplished at a rate effective for preventing such transition from causing an emissions affecting pressure surge in the second steam delivery system.
5. The plant of Claim 1 further comprising:
outlet means effective for connecting effluent outlet of each unit's Claus reactor with inlet means for each other unit.
outlet means effective for connecting effluent outlet of each unit's Claus reactor with inlet means for each other unit.
6. The plant of Claim 1 wherein each unit comprises:
inlet means comprising a first inlet line for connecting effluent outlet of Claus catalytic reactor of another unit in flow communication therewith and a second inlet line for connecting effluent outlet of Claus catalytic reactor of yet another unit in flow communication therewith; and outlet means comprising valved lines for connecting effluent outlet of Claus catalytic reactor thereof in flow communication with one of inlet means of another switching unit and inlet means of yet another switching unit and tail gas line.
inlet means comprising a first inlet line for connecting effluent outlet of Claus catalytic reactor of another unit in flow communication therewith and a second inlet line for connecting effluent outlet of Claus catalytic reactor of yet another unit in flow communication therewith; and outlet means comprising valved lines for connecting effluent outlet of Claus catalytic reactor thereof in flow communication with one of inlet means of another switching unit and inlet means of yet another switching unit and tail gas line.
7. In a sulfur recovery plant comprising:
at least three units connectable for sequentially processing gas for formation and removal of sulfur therefrom;
each unit having a Claus catalytic reactor periodically operated under effective high temperature Claus conditions and periodically operated under effective cold bed adsorption conditions;
each Claus catalytic reactor of each unit having an upstream sulfur condenser associated therewith for cooling process gas to said Claus catalytic reactor during operation under cold bed adsorption conditions;
each unit comprising a Claus catalytic reactor and associated upstream condenser being periodically alternated between operation under effective high temperature Claus conditions and effective cold bed adsorption conditions;
means for periodically connecting shell side of each inlet sulfur condenser to a first pressure steam delivery system and to a second pressure steam delivery system, the first pressure being greater than the second pressure.
at least three units connectable for sequentially processing gas for formation and removal of sulfur therefrom;
each unit having a Claus catalytic reactor periodically operated under effective high temperature Claus conditions and periodically operated under effective cold bed adsorption conditions;
each Claus catalytic reactor of each unit having an upstream sulfur condenser associated therewith for cooling process gas to said Claus catalytic reactor during operation under cold bed adsorption conditions;
each unit comprising a Claus catalytic reactor and associated upstream condenser being periodically alternated between operation under effective high temperature Claus conditions and effective cold bed adsorption conditions;
means for periodically connecting shell side of each inlet sulfur condenser to a first pressure steam delivery system and to a second pressure steam delivery system, the first pressure being greater than the second pressure.
8. The plant of Claim 7 further comprising:
means for causing the units to alternate in a sequence effective for periodically causing high pressure to low pressure transitions to occur in steam side of each unit's sulfur condenser; and means for placing each condenser during such transition in a position feeding a Claus catalytic reactor operated under high temperature Claus conditions where such transition can be accomplished at a rate effective for preventing such transition from causing an emissions affecting pressure surge in the second pressure steam delivery system.
means for causing the units to alternate in a sequence effective for periodically causing high pressure to low pressure transitions to occur in steam side of each unit's sulfur condenser; and means for placing each condenser during such transition in a position feeding a Claus catalytic reactor operated under high temperature Claus conditions where such transition can be accomplished at a rate effective for preventing such transition from causing an emissions affecting pressure surge in the second pressure steam delivery system.
9. In operation of an extended Claus process plant having at least first, second, and third Claus catalytic reactors with associated upstream first, second, and third condensers respectively associated therewith, each condenser being periodically switched from a first pressure steam delivery system to a second pressure steam delivery system, each reactor periodically being alternated between high temperature Claus operation and cold bed adsorption operation at a first temperature and cold bed adsorption at a second temperature lower than the first temperature, the steps comprising;
periodically switching each condenser from the first pressure steam delivery system to the second pressure steam delivery system causing each such condenser periodically to undergo a high pressure to low pressure transition, and during such transition period placing each condenser in a position where the transition can be accomplished at a rate effective for avoiding an emissions affecting pressure surge in the second pressure steam delivery system.
periodically switching each condenser from the first pressure steam delivery system to the second pressure steam delivery system causing each such condenser periodically to undergo a high pressure to low pressure transition, and during such transition period placing each condenser in a position where the transition can be accomplished at a rate effective for avoiding an emissions affecting pressure surge in the second pressure steam delivery system.
10. The method of Claim 9 further comprising:
placing each condenser during the transition period in a position feeding process gas to the first of the three catalytic reactors through which process gas is passed in sequence;
bypassing process gas around the sulfur condenser feeding the first of the three catalytic reactors; and causing the high pressure to low pressure transition to occur during the period process gas is bypassed around the sulfur condenser feeding process gas to the first of the three catalytic reactors.
placing each condenser during the transition period in a position feeding process gas to the first of the three catalytic reactors through which process gas is passed in sequence;
bypassing process gas around the sulfur condenser feeding the first of the three catalytic reactors; and causing the high pressure to low pressure transition to occur during the period process gas is bypassed around the sulfur condenser feeding process gas to the first of the three catalytic reactors.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US443,789 | 1989-11-30 | ||
| US07/443,789 US5015460A (en) | 1989-11-30 | 1989-11-30 | Condenser-reactor switching units for extended Claus process |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2026548A1 CA2026548A1 (en) | 1991-05-31 |
| CA2026548C true CA2026548C (en) | 1998-06-02 |
Family
ID=23762213
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002026548A Expired - Lifetime CA2026548C (en) | 1989-11-30 | 1990-09-28 | Condenser-reactor switching units for extended claus process |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US5015460A (en) |
| CA (1) | CA2026548C (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5141733A (en) * | 1989-11-30 | 1992-08-25 | Pendergraft Paul T | High pressure-low pressure steam system for extended Claus sulfur recovery plant |
| JP5121927B2 (en) * | 2007-06-21 | 2013-01-16 | フルオー・テクノロジーズ・コーポレイシヨン | Air demand feedback control system and method for sulfur recovery unit |
| KR101058680B1 (en) | 2007-12-21 | 2011-08-22 | 재단법인 포항산업과학연구원 | The process adding medium temperature sulfur Reactor in the process of Claus plant and the manufacturing method |
| US7658906B2 (en) * | 2008-02-28 | 2010-02-09 | Conocophillips Company | Sulfur recovery plant |
| US8815203B2 (en) | 2012-08-08 | 2014-08-26 | Black & Veatch Holding Company | Cold bed adsorption sulfur recovery process |
| WO2014204953A1 (en) * | 2013-06-21 | 2014-12-24 | Phillips 66 Company | Process for in-situ production of low dissolved hydrogen sulfide, degassed, sulfur from claus sulfur recovery |
| US9138675B2 (en) | 2013-06-21 | 2015-09-22 | Phillips 66 Company | Process for degassing condensed sulfur from a claus sulfur recovery system |
| US11530131B1 (en) | 2021-11-16 | 2022-12-20 | Saudi Arabian Oil Company | Methods and systems of sub-dew point sulfur recovery with interstage membrane units |
Family Cites Families (29)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2767062A (en) * | 1951-02-07 | 1956-10-16 | Texas Gulf Sulphur Co | Method for producing sulfur |
| CA938087A (en) * | 1970-04-30 | 1973-12-11 | Amoco Canada Petroleum Company Ltd. | Treatment of sulfur plant effluent to avoid atmospheric pollution |
| US3702884A (en) * | 1970-05-22 | 1972-11-14 | Amoco Prod Co | Method for reducing sulfur compounds in sulfur plant effluent |
| USRE28830E (en) * | 1970-05-22 | 1976-05-25 | Amoco Production Company | Method for reducing sulfur compounds in sulfur plant effluent |
| US3758676A (en) * | 1971-06-21 | 1973-09-11 | Amoco Prod Co | Method for recovery of elemental sulfur from sour gas |
| US3749762A (en) * | 1971-08-02 | 1973-07-31 | Amoco Prod Co | Process for producing sulfur from sour gas |
| US4029753A (en) * | 1976-01-12 | 1977-06-14 | Ralph M. Parsons Company | Sulfur plant temperature control |
| US4035474A (en) * | 1976-03-01 | 1977-07-12 | Standard Oil Company (Indiana) | CBA for Claus tail gas cleanup |
| IT1077827B (en) * | 1976-03-01 | 1985-05-04 | Standard Oil Co | IMPROVEMENT IN THE REGENERATION PROCEDURES OF CATALYTIC REACTORS CONTAMINATED BY SULFUR |
| US4124696A (en) * | 1977-11-07 | 1978-11-07 | Standard Oil Company (Indiana) | Method for sealing leakage across valves in a sulfur recovery plant |
| US4180554A (en) * | 1978-08-14 | 1979-12-25 | Standard Oil Company (Indiana) | Method for removal of sulfur deposited on a Claus catalyst |
| DE2923895C2 (en) * | 1979-06-13 | 1982-01-28 | Davy McKee AG, 6000 Frankfurt | Process for removing hydrogen sulfide and sulfur dioxide from Claus exhaust gases |
| US4426369A (en) * | 1981-03-02 | 1984-01-17 | Standard Oil Company (Indiana) | Low temperature Claus process with water removal |
| US4430317A (en) * | 1981-03-02 | 1984-02-07 | Standard Oil Company (Indiana) | Low temperature Claus process with water removal |
| US4391791A (en) * | 1981-04-09 | 1983-07-05 | Standard Oil Company (Indiana) | Low temperature sulfur recovery |
| US4391790A (en) * | 1981-09-28 | 1983-07-05 | Standard Oil Company (Indiana) | Method and apparatus for reducing the ammonia concentration of sulfur recovery facility gas streams |
| US4400369A (en) * | 1982-04-19 | 1983-08-23 | Standard Oil Company (Indiana) | Apparatus and process for recovering heat emanating from the shell of a thermal reactor in a sulfur recovery plant |
| US4462977A (en) * | 1982-04-26 | 1984-07-31 | Standard Oil Company (Indiana) | Recovery of elemental sulfur from sour gas |
| US4601330A (en) * | 1983-05-31 | 1986-07-22 | Amoco Corporation | Cooling and condensing of sulfur and water from Claus process gas |
| US4526590A (en) * | 1983-05-31 | 1985-07-02 | Standard Oil Company (Indiana) | Cooling and condensing of sulfur and water from Claus process gas |
| US4473541A (en) * | 1983-05-31 | 1984-09-25 | Standard Oil Company (Indiana) | Low water content sulfur recovery process |
| US4483844A (en) * | 1983-07-29 | 1984-11-20 | Standard Oil Company (Indiana) | System and process for producing elemental sulfur |
| US4487754A (en) * | 1983-07-29 | 1984-12-11 | Standard Oil Company (Indiana) | System and process for producing and recovering elemental sulfur |
| US4482532A (en) * | 1983-07-29 | 1984-11-13 | Standard Oil Company (Indiana) | System and process for producing elemental sulfur |
| US4508698A (en) * | 1983-08-30 | 1985-04-02 | Standard Oil Company (Indiana) | Process and system for producing and recovering elemental sulfur |
| US4507275A (en) * | 1983-08-30 | 1985-03-26 | Standard Oil Company (Indiana) | Process for producing and recovering elemental sulfur from acid gas |
| US4643888A (en) * | 1985-03-21 | 1987-02-17 | Amoco Corporation | Process and apparatus for recovery of sulfur from ammonia containing acid gas streams |
| US4684514A (en) * | 1985-07-22 | 1987-08-04 | Air Products And Chemicals, Inc. | High pressure process for sulfur recovery from a hydrogen sulfide containing gas stream |
| US4756900A (en) * | 1987-01-14 | 1988-07-12 | Amoco Corporation | Recycling of waste heat boiler effluent to an oxygen-enriched Claus reaction furnace |
-
1989
- 1989-11-30 US US07/443,789 patent/US5015460A/en not_active Expired - Lifetime
-
1990
- 1990-09-28 CA CA002026548A patent/CA2026548C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| US5015460A (en) | 1991-05-14 |
| CA2026548A1 (en) | 1991-05-31 |
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